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Патент USA US2107327

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Feb. 8, 1938.
2,107,327
T. A. cRElGHToN
METHOD FOR CEMENTING WELL CASINGS
Filed Oct. l, 1957
il«íëL
v
PatentediFeb. s, 1938
UNITED STATES '
PATENT OFFICE
2,101,327
l
METHOD Fon CEMENTING WELL cAsmGs
Thomas A. Creighton, Long Beach, Calif., as
signor of one-half to Jesse C. Wright, Los
Angeles, Calif.
Application October 1, 1937, Serial No. 166,790
9 Claims. (C1. 16B-21)
This invention relates to a method useful in
well drilling operations and relates more particu
larly to a method for cementing casing in a Well.
A general object of this invention is to provide a
5
simple, rapid and commercially practical method
for cementing casing in a well.
In the drilling of deep wells such as oil wells,
gas wells, etc. it is usually necessary to line
or case the well with a casing to support the wall
of the well and to exclude unwanted fluids from
the well. It is the common practice to cement
the lower portion of the casing in the well to pre
vent the contamination of the fluid to be pro
duced and to prevent both the upward and down
r ward passage of ßuid around the set casing. In
the methods now usually employed to cement a
casing in a well the casing is run into the well to
its ñnal position and cement is then pumped down
through the casing,»or through a tube within
the casing, to the bottom of the well and is
forced up around the lower portion of the casing
by the pump pressure. In the rotary method of
well drilling the well and the casing are filled
with the mud-laden drilling fluid and the cement
05 is contaminated with this drilling fluid when it is
pumped through the casing and forced up around
the lower end of the casing. As the cement is
forced up around the lower end of the casing it
mixes with the mud on the casing and on the
Wall of the Well and follows the paths of least
resistance leaving channels or spaces occupied by
mud and other foreign material. This so-called
“channeling” of the cement that encases the
lower portion of the casing often results in the
leakage of water or other unwanted fluid into the
well and necessitates expensive and'time consum
ing operations to stop». the leakage around the
casing.
Another object of this invention is to provide
40 a method for cementing a casing in a well that
assures a full and eiîective shut-off around the
casing.
Another object of this invention is to provide a
_ method for cementing well casing that avoids the
“channeling” of the cement.
Another object of this invention is to provide
a method for cementing a well casing in which
the cement is contaminated by mud, cuttings,
50 etc. to a minimum extent.
Another object of this invention is to provide
` a method for cementing a'well casing in which it
is unnecessary to pump the cement up around
the casing shoe whereby the cement is free to
flow at a slower rate and to completely occupy
the annular space around the casing to form a
tight, effective shut-off.
A further object of this invention is to pro
vide a method for cementing well casing that is
easy to perform and that does not necessitate the Ul
employment of expensive equipment.
The various objects and features of my in
vention will be fully understood from the follow
ing detailed description of a typical preferred
manner of carrying out the method of the in 10
vention, throughout which description reference
is made to the accompanying drawing, in which:
Fig. 1 is a longitudinal sectional view of the
lower portion of a well illustrating the cement
being delivered to the well in accordance with the 15
method of the invention. Fig. 2 is a view similar
to Fig. 1 showing the casing about to enter the
cement and Fig. 3 is a view similar to Fig. 1
with the lower portion of the casing in vertical
cross section and showing the casing set in the 20
cement.
In the drawing I have illustrated the open or
uncased lower portion of a typical well W. It will
be assumed that the well is being drilled by the
rotary method and is iilled with the rotary mud M 25
usually employed in the rotary method of drilling.
As illustrated in Fig. 1 of the drawing a string of
drill pipe P is in the well W and carries at its
lower end a drilling tool T. The tool T may have
drilled the well W to the desired depth. In ac 30
cordance with the usual practice the well drilling
tool 'I' has circulation ports I0 for discharging the
drilling fluid or rotary mud M.
The method provided by the present invention
includes, generally, the passage or delivery of the 35
proper amount of cement Il to the lower portion
of the well W through the drill pipe P, the re
moval of the drill pipe P and the tool T from the
Well, providing a casing C having a closure or a
valved shoe S on its lower end and having a 40
suitable float valve V, and then running the cas
ing C into the well W to its final position in the
well to displace the cement Il upwardly around
its lower end wherebyv the lower portion of the
casing is embedded in the cement.
45
In accordance with the present invention the
drill pipe P may be .employed to deliver or con
duct the cement mixture or cement slurry to the
bottom of the well W. When the well W has been
drilled to the desired depth and while the -drill 50
pipe P remains in the well bore the cement Il
may be passed down through the pipe. In prac
tice the cement slurry Il is pumped Vthrough the
drill pipe P by suitable pumping equipment. The
cement I l discharges from the ports I0 of the 55
2
2,107,8‘27
drilling tool T toñow into the lower portion of
the well. Thus the cement Il, in the quantity
shoe S and the lower portion of the casing enters
the cement Il. As described above, the cement
previously determined, is delivered to the bottom '
II is retarded so that it remains in a fluid or
of ,the well bore W with little or no contamina
plastic state until the casing C is embedded in\~it.
The valve I4 in the shoe S prevents the cement
tion. The drill pipe P conducting the cement
_II of course prevents the mud M in -the well W
from contaminating the cement II las it is de
livered downwardly into the well.
\
The character of the cement I I delivered to the
10 lower portion of the well W is of particular im
portance to the method of the invention. In ac
cordance with the invention Portland cement is
employed that is retarded to attain its initial set
in from 30 to 40 hours after mixing. When the
II from entering the casing C so that the casing
displaces the cement II upwardly into the annu
lar space X between the casing and the wall of
the well W. During the~passage of the casing C
into or through the cement -II it is preferred to
lower the casing C slowly so that the cement is
made to slowly move upwardly around the casing
C ln the space X as it is displaced by the slow
moving casing. It is believed that it will be
15 required quantity of cement I I has been pumped
readily understood how the casing C provided
into the'well W through the drill pipe P the drill
pipe carrying the tool T is withdrawn from the
with the valved shoe S displaces the cement I I to
iiow upwardly in the‘space X around the casing.
When the casing C is in its ñnal position in the
well the cement II is allowed to set and the ce
well. It is to be particularly noted that the ce
ment II is delivered to the lower portion of the
20 well W in an~ uncontaminated state without the
necessity of runninga special cementing string
into the well. As .the drill pipe P is already in
the well at the start of the cementing operation
Vthe employment of the pipe P to conduct the
cement effects a marked saving in time.
Immediately following the withdrawal of the
drill pipe P and the tool T from the well the
casing C is assembled and run into the well. The
shoe S on the lower end of the casing C is pro
30 vided with means for preventing the entrance
of ñuid into the casing when the same is run into
4the well, whereby the casing C may be iloated
into the well. In the particular case illustrated
in the drawing the shoe S has a cage I2 provided
35 with a valve seat I3 and a ball valve I4 co
operates with the seat I3 to close the lower end
of the casing C. The valve V may be provided
in the casing C to assure that the casing may
be floated into the well in the event the valved
40 shoe S leaks. The float valve V may be' of typical
construction and is designed to positively pre
vent up-ñow in the casing C and to trap or sup
port a substantial head of fluid in the casing.
'I'he valve V may be mounted or arranged in one
45 of the couplings I5 of the casing and may be
provided at any desired point in the lower por
tion of the casing. The valve elements I2, I3 and
I4 of the casing shoe S and the iloat valve V are
formed of frangible or drlllable material so that
they may be readily drilled out when the well is
to be completed or deepened. The valve V may
be of any typical construction and any suitable
form of valved shoe S or closure may bel em
ployed on the lower end of the casing C. Ac
cordingly, the invention is not to be considered
as restricted to the use of the particular/vw
'structures illustrated in the drawimg.
The casing C equipped with the valved shoe S
and the iloat valve V, as described above, is run
60 into the well W in the usual manner. The valved
shoe S and the valve V positively prevent the
up-flow of fluid _in the casing C and permit the
casing to be floated vinto a deep well without dan
ger o1' parting through its own Weight. In float
ing the casing C into the well W the valve V and
the valved shoe S prevent the entrance of the
- mud M tothe casing so that the hollow or empty
casing has sutllcient buoyancy to support itself
against parting. It may be necessary to pour
-mud or other iluid F into the empty casing C to
give it sufñcient weight so that it may be run
into the well. The casing C may be run through
the well to its final position.
«
During the latter portion of the downward
movement of the casing C into the well W the
menting operation is complete. It is to be under 20
stood that the valve V, the valve elements I2, I3
and I4 in the shoe S, and any other internal
parts of the shoe S may be removed or broken
»out to permit the testing of the cement seal and
the casing C and to permit completion of deepen 25
ing of the well.
The method provided by the present invention
for cementing well casing prevents “channeling”
of the cement due to pumping of the cement up
wardly around the lower end of the casing and 30
thus assures an eiîective iluid tight seal. The
method may be readily carried out without em
ploying special packers, etc. The cement II is
delivered to the lower portion of the well W
through the drill pipe P so that it is not con
taminated by the mud or iluid M in the well. The
lowering of the casing C into the mix or body of
plastic cement II in the bottom of the well bore
W assures the complete embedding of the lower
portion of the casing C in the cement so that
ñuid cannot possibly leak or ilow through the an
nular space X between the casing and the wall
of the well.
-
Having described only a typical preferred man
ner of carrying out the method of my invention,
I do not wish to be limited or restricted to the
speciñc details herein set forth, but wish to re
serve to myself any variations or modifications
that may appear to those skilled in the art or
fall within the scope of the following claims:
Having described my invention, I claim:
1. The method of cementing a casing in a well
comprising, depositing a body of plastic cement
in the well, and then running the casing into the
well to enter it in the cement.
55
2. 'I'he method of cementing a casing in a
well comprising passing a body of plastic cement
to the lower portion of the well, providing the
casing with a. closure at its lower end, and run
ning the casing into the well to immerse its lower 60
portion in the plastic cement.
`3. 'I'he herein described method comprising
depositing a body of plastic cement in a well by
passing the cement down through a tubular drill
ing string in the well, removing the drilling string 65
from the well, running a casing into the well to
introduce its lower end into the cement, and then
allowing the cement to set.
4. The well drilling method comprising oper
ating a tubular well drilling string in a well, 70
passing plastic cement through the string to the
lower portion of the well to occupy the same, re
moving the drilling string from the well, lower
ing a well casing into the well to introduce the
casing into the cement and cause the upward dis 75
2,107,327
placement of the cement around the casing, and
then allowing the cement to set.
5. The well drilling method comprising operat
ing a tubular well drilling string in a well, pass
ing plastic cement through the string to the' lower
portion of the Well to occupy the same, removing
the drilling string from the well, lowering a cas
ing having a closed lower end into the well to
enter its lower portion in the cement and there
10 by cause the upward displacement of the cement
around the casing, and then permitting the ce
ment to set.
'
6. The method of cementing a. casing in a well
comprising delivering a mass o! plastic cement
to the lower portion of the well, providing a cas
ing with a valved lower end, running the casing
into the well so that its lower portion enters the
cement and 'displaces the cement upwardly
around the casing, and then allowing the cement
20 to set.
7. The method of cementing 'a casing in a well
comprising delivering a mass of retarded plastic
cement to the lower portion of thewell, provid
ing a casing with a closed lower end, running the
casing into the well so that its lower portion en
ters the cement anddisplaces the cement up
wardly around the casing, and then allowing
the cement to set.
8. The method of cementing a casing in a well
comprising, delivering a mass of retarded plas
tic cement to the bottom of the well, ñoating a
casing into the well to enter the cement and
displace the cement upward around the casing
and then allowing the cement to set.
'9. The well drilling method comprising oper
`ating‘a tubular well drilling string in a well, pass- ,
ing retarded plastic cement through the string to
the lower part of the well, removing the drilling
string from the well, providing a casing with a
valved shoe on its lower end, floating the casing
into the well sov that its lower portion enters the
cement and displaces the cement upwardly
around the casing, lowering the casing to its 20
final position in the well, and then allowing the
cement to harden.
`
THOMAS A. CREIGHTON.
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